This application claims priority under 35 U.S.C. xc2xa7xc2xa7 119 and/or 365 to 98108681.2 filed in Europe on May 13, 1998; the entire content of which is hereby incorporated by reference.
1. Field of the Invention
The invention relates to a method and a device for increasing a data throughput in network applications for the transmission of data at high speed via a packet oriented cordless data network.
2. Background Information
A known network for the transmission of data at high speed is a packet data network, such as the internet. The internet is a global network consisting of a multitude of individual local networks, which are connected with other networks via fixed lines or switched connections. Moreover, the internet is defined by the use of an internet protocol (IP) and the addressing thereof. An associated protocol family, the so-called TCP/IP (transmission control protocol/internet protocol) is also used in the internet and constitutes an essential feature of the internet. The interconnection by using the internet protocol forms the internet. Furthermore, the internet is not maintained or controlled by a central place. Specific servers take care of the international routing. The structure of the network as such cannot be illustrated and is unknown due to the unplanned grown structure. The path of data packets to be transmitted can, therefore, not be predetermined. They are passed on from router to router, whereby now and then also detours are made. Since also consecutive data packets in an application can take different paths, consecutively sent data packets are received at the target address at different times.
The delivery of data packets in the internet and their sequences are guaranteed by the TCP (transmission control protocol) service. The receiver submits positive receipts to the transmitter, or the repetition of damaged or lost data packets is demanded. All data packets sent are continuously numbered for being able to recognize the loss of individual data packets or to newly demand lost data packets. On the receiving side the data packets are reassembled. As the internet protocoll (IP) is based on the connectionless transport of data, individual data packets can get lost during the transport or can reach the receiver in the wrong order. One task of the TCP is to repeat data packets unless the receipt is acknowledged within a specified time (xe2x80x9cTechnik der Netzexe2x80x9d; G. Siegmund; R. v. Decker""s Verlag; Heidelberg 1996; Chapter 6).
In network applications for the transmission of data at high speeds via a packet oriented data network the data packets, for instance, arc held at an intermediate node between the two networks, where they are lined up in a waiting queue due to the different bandwidth of the networks, and corresponding to their time of receipt they are made available for further transmission. According to the explanations in the prior art a data packet is requested anew every time its receipt is not acknowledged within a specified time. It is, however, possible that the data packet has already been received in the intermediate node, but that it is available for further transmission in the wrong sequence, i.e. at a later time. The repeated request consequently causes an additional and unnecessary burden, as the missing data packet already exists, waiting for further transmission in the waiting queue.
Furthermore, when requesting the transmission of one or more missing data packets, the newly transmitted data packet becomes last in the sequence, which is why a so-called time-out can occur. The time-out results in the stop of the transmission. In order to restart the transmission after such a time-out a starting mechanism is required, which is slow and whereby the data throughput is reduced altogether.
It is, therefore, the object of the present invention to provide a method and a device by means of which the unnecessary repeated request for data packets as well as time-outs are avoided.
It is an advantageous aspect that an unnecessary burden is avoided in that already existing data packets need not be requested anew, wherein the data throughput is reduced.
It is, moreover, advantageous that the data throughput is increased by avoiding time-outs.
It is another advantageous aspect of the invention that data packets are already sorted at an intermediate node, thereby being available for further transmission in a sorted manner.
According to the present invention it is especially advantageous that the data packets are sorted at any time, wherein a new request can be avoided at any time.
It is, moreover, advantageous according to the present invention that a certain number of data packets is sorted and that a new sorting process takes place again only after said data packets have been transmitted. Accordingly, the sorting process is further optimized.